Accessing Encrypted Archives

I want to write a password program using C++ that will check the entered password against a file in an encrypted archive to see if it's correct. The archive is fingerprint accessible, but also has a backup password, which I'm assuming would be used. How do I get through the password barrier on the archive to check the file in the archive? Somehow I don't think std::fstream would do the trick.

开发者_高级运维OS: Windows XP

Compiler: MS Visual Studio 9.0 Express. I also have boost installed if needed.

Encryption: biometric Protector Suite QL that came with my Sony VAIO, .ueaf extension on the archive

The crucial information missing is what kind of archive this is. Once you know that look for a library supporting this kind of archive. If it is no popular archive format and there is no library you need to find out what kind of encryption algorithm is used and how exactly it is applied, then use that information to decrypt the contents of the archive "by hand".